Exhaust passage of two-stroke internal combustion engines



April 30, 1940. M. KADENACY a 93.7

EXHAUST PASSAGE QF TWO-STROKE iNTERNAL comsus'rlori ENGINES F iled Jun 1, 1936 3 Sh96tS Sh69t 1 I 72 Aaeva'cy- A ril 30, 1940. M. KADENACY v 1 2,198,730.

EXHAUST PASSAGE OF TWO-STROKE INTERNAL COMBUSTION ENGINES Filed June-.1, 1936 s Sheets-Sheet 2 Fig.5

fivm 7n. kavole varcy' Patented Apr; '30, 1940 I STATES TR-ATE I I ExnAUsT rssszr zl-rwo-sraoxn it NT .oFFicE- g" INTERNAL COMBUSTION ENGINES in c Michel Kadenacy, Paris, France; assignor- Armstrong" Whitworth Securities Company, a:

Limited, London, England Application June 1,1936, Serial no,- 82,959

.In Great Britain January 11, 1936 f I: N a 6 Claims. (Cl. 60-32 v e 7 c Thisi-nvention relates to improvementsin th'e exhaust passage of two-stroke cycle internal combustion engines of the kind wherein at least a a substantial portion of the burnt gases leaves the cylinder at a speed much higher than that obtaining when a flow resulting from an adiabatic expansion'only is involved, and in such 'a short interval of time that it is discharged as a mass leaving a depression behind it which is utilised in I 1'0 introducing a fresh charge into the cylinder by opening the inlet orifice with the required delay after the opening of the exhaust orifice to ensure that the burnt gases are then moving outwardly through the exhaust orifice or duct and that a 16, suction efiect is exerted at the inlet orifice as a consequence of the exit'of the said mass.

It is specified inmy U. S. Patent No. 2,130,721'

issued September 20, 1938, that /the area of the inlet ports, and the duration of opening of these 2b ports, in relation with the characteristics of the e'xhaust'system, must be suflicient to permit the charge to fill the cylinder and enter the exhaust system in the time available before the return of the burnt gases occurs; provision must be made to ensure that the charge will be retained in the cylinder and will not be forced out by the return of the burnt gases towards the cylinder and that the charge will not be sucked out by a prolonged outward movement of the issuing mass of burnt ases.

I The object of the present invention is to provide improved meanswhereby the objectionable influence of the return of the burnt gases onthe contents of the cylinder may be destroyed while tliie phenomena-in question in charging the enne.

A- further object o! the invention is-to provide improved means wherebyin addition any objec- 4o ..tionable influenceor, a prolonged suction in the \exhaust systemon'thecontents of the-cylinder may be avoided while still pr'mittingithedesired utilisation to be madeof the tion in charging the engine.

- structing the exhaust system of 'an internal combustion engine of the kind setforth that it permits the free and unrestricted outward motion of the issuing mass of burnt gas'esfpushing b fore it all the gases in its path, until 'it reaches 3 p edetermined {which is located not further from the cylinder than the zone from which the return of the burnt gases would occur and there imparts gyratory which:

ment of the invention, showing the'mounting, oi

thereof a device constructed in accordance with permitting the desired utilisation to be made of a second embodiment of the invention, the device thereof a device constructed in accordance with phenomena in ques- The invention consists in soarrah h cylinder l, in which moves a piston controlling '5 for the introduction ofthe combustible-fuel and position in the exhaust system' motion to the said gases as a whole, which all rotate substantially in said positions o that any,

and may destroy or' attenuate the return at this point.

A location intermediate the. cylinder'and the said zone of return mayevidently be chosen for the said device, and in a preferred and advantageous embodiment" of the invention the said location will be so chosenthat the volume of the de'- pression or void left in the exhaust system will be restricted to-an amount such that the entering charge can always till the cylinder and the depression or void left in the exhaust system.

whereby in addition to destroying ,or attenuating the return of the burnt gases any objectionable effect of a prolonged outward movjeinentot the said cases will be annulled. 1 I Some embodiments of the invention'will now be described by way of example only and with reference to the accompanying drawings. in 25 ure 1 is an axial section through a device constructed in accordance with 'a first embodithe device upon an engine cylinder. '30

Figure 2 is'asection on the line II'-- I I in Figure 1. Y v

ure 3 is 'a diagrammatic representational an'engine haying disposed in the exhaust conduit being shownin axial section. Figure 4 is'adiagrammatic representation of an engine having disposed in the exhaust conduit '40 a third embodiment of the invention, the device :being shown in axial section.

In the drawings the invention, simply by way of example is applied to an engine comprising a inlet orificesr3 situated at the base of the cylinder and communicating with an inlet duct 4, and

having at the head of the 'cylinder aninjector 0 an exhaust orifice -6, communicating with an exhaust duct 1 and controlled by a poppet valve 8 operated by a push rod 9 and rocker arm i0, from the engine shaft Il.'

It is to beunders t this enging is given by way of example only and that it will have the timing of inlet opening hereinbefore specified.

The device illustrated in fitted close to the engine cylinder. It will be seen that the gases issue from the cylinder through the exhaust orifice 6 into a short neck or nozzle H, from which they enter the exhaust duct 1 proper. This nozzle I2 is surrounded by a chamber l3 containing an arrangement of. guiding vanes l4 and communicating with an annular space 15 left between the outlet end of the nozzle l2 and the entry to the exhaust pipe 1, and the arrangement is such that the returning gases are guided and directed into this chamber l3 and are given a rotary or helical motion by the vanes H whereby the action of the return of the gases is annulled or very greatly attenuated immediately before reaching the cylinder.

With the arrangement illustrated in Figures 1 and 2 it will be understood that the mass of burnt gases issuing from the cylinder is free to travel outwards through the exhaust duct until its movement is reversed in direction and that device protects the cylinder from the action of the returning gases but offers no protection against the action of a prolonged suction on the contents of the cylinder. A deflector ii! is placed at the outlet end of the nozzle l2, and is so formed that it does not impede the outward movement of the burnt gases, but assists in guiding returning gases into the chamber [3.

In the arrangement illustrated in Figure 4 the exhaust pipe leads into an elongated chamber Ill-having an inner space ll into which the gases enter, an outer space 18 communicating with an extension I9 of the exhaust pipe and a tubular ring or" vanes 20 separating the two spaces I! and 18. The space ll is closed at its outer end 2! so that the gases cannot pass directly through but are compelled to'issue through the vanes 23. In this example it is to be understood that the chamber 15 will be situated in the exhaust duct at the zone from which the return of the burnt gases would occur, and that with any particular exhaust system, this zone can be determined.

As this zone varies somewhat according to the intensity of theexplosion, the device will be so situated that it will still be effective when the zone from which the return occurs varies within chosen limits.

Atthe moment at which the return of the burnt gases occurs there is a violent reaction in the two directions towards and away from the cylinder, and by placing an arrangement such as that shown in Figure 4 at this zone, this reaction is allowed to exert its effect outwardly so that the gases are forced through the vanes into the. outer chamber 18 in which they are given a rotational motion as a whole as a consequence :of their passage through the vanes which will vbe suitably arranged for this purpose. Thereafter when this rotational motion dies down. the gases will expand and flow through the.extens ion pipe I9.

ln this construction any action 01 the return .oithe burnt gases on the cylinder is prevented but the suction is allowed to exert its full action and .may have an objectionable action on the ylinder under certain conditions.

The device illustrated in Fi'gureS is fitted in the exhaust pipe 1 at a point between the cylinder. and-the zone from which the return or the burnt gases would occur. In this example, the burnt gases, after travelling a predetermined distance along the exhaust pipe I enter the pas- Figures 1 and 2 is sage 22 closed at its outer end 23 and are guided by vanes 24 into a chamber 25, the vanes 20 being so arranged as to impart rotational motion as a whole to the issuing mass of burnt gases as in' Figure 4, the gases passing ultimately into the extension 25 of the exhaust pipe.

It will be seen that provided this device is placed between the cylinder and the zone in the exhaust pipe from which the return of the gases would occur, the position of the device will determine the volume of the depression or void left in the exhaust pipe by the issuing mass of burnt gases.

If this device is placed at such a distance from the cylinder that the volume of the depression or void left by the mass exit of the burnt gases is such that the charge entering the cylinder always fills the cylinder and fills this depression or void, then the objectionable actions of the return of the burnt gases and of a prolonged outward movement will both be avoided.

Such an arrangement will be of particular advantage when applied toan engine in which the inlet port is closed before the exhaust port closes, since in such an engine the return of the burnt gases may foul the charge at low speeds and a prolonged suction may draw the charge out of the cylinder through the exhaust ports at high speeds. With an arrangement constructed and arranged as described with reference to Figure 3, both these objections may be avoided in such an engine without resorting to any special timing of exhaust and inletv closures.

In principle, and when the chief requirement is that of protecting the cylinder from the abrupt return of the burnt gases into the cylinder, it is advantageous for the operation of the engine for the exhaust to occur as rapidly as possible andv for the time of duration of the admission period to be lengthened.

The volume of the depression or void engendered by the issuing mass of burn gasesmust e as great as possible for the same c di ns of intensity of the explosion. For this purpose a free path must be allowed over the whole P sible trajectory for the column of the exhaust gases.

The constructions illustrated byway of example in Figures 1 and 2, and m Figure- 4, permit this result to be obtained. But in certain 5 cases and particularly in en in which eX- haust close: after inlet and at high engine speeds, the total duration 01' the suction and the volume of the depression or void left in the exhaust. sys- I tem may be such'that this volume cannot be filled during the charging period, and that there is a tendency for the charge to be drawn out or the cylinder into the exhaust system. I I

In such a case itis advantageous to employ an arrangement such as thatshown in Figure 3,4 wherein a" certain proportion of the depression orvoid thatoan be left in the exhaust system by the issuing mass of gasesis utilised for the purpose of pas in fresh chargethrough the cylinder and th y ling the latter, wlille at t e same time the objectionable action of (tire;- turn of the burnt gases or or a prolonged out,- ward movement of the burnt gases is avoided;

h devices described with reference to F19 -ures 3 and 4', while annulling the action of th' return of the-gases, also prolong theduratio, of the depression or void in thecylinder and 1;! t ing; of the exhaust system by retardinl the destruction of this depression or.void, bythe g5 can always be substantially filled by the entering charge, whereby any action of the return of thereversal of the movement of the gases in the exhaust system.

A further advantage of the arrangement described with reference to Figure 3 is that the rotation imparted to the gases in the exhaust duct may be so prolonged that it still continues when the next exhaust phase occurs.

The effect of this will be to maintain a depression in the exhaust pipe outside the exhaust orifice, so that exhaust will occur ina reduced Period of time.

I claim:

1. Method of controlling two-stroke cycle in-- ternal combustion engines, which comprises establishing communication between the cylinder and exhaust system during the firing stroke, providing forthe issuance of the burnt gases from the cylindersubstantiallyas a mass in an in- 'further from the cylinder than the zone from which the return of the burnt gases would occur, and at such position imparting a gyratory motion to the said gases as a whole, which all rotate substantially in said position so that any subsequent rectilinear motion of the gases is hindered until the exhaust orifice is closed, maintaining the admission orifice closed until the said issuance of the mass-of burnt gases is in full progress and admitting fresh charge into the cylinder when the said issuance of the burnt g'ases is in full progress and causes a suction effect to be exerted in. the cylinder, while the exhaust port is still open.

2. Method of controlling two-stroke cycle internal combustion engines, which comprises establishing communication between the cylinder and exhaust system during the firing stroke, providing for the issuance of the burnt gases from the cylinder substantially as a mass in an interval of time shorter than that which would be required for the burnt gases to expand down to the ambient pressure by. adiabatic flow,- whereby the mass of gases moves outward and thereafter returns, permitting the. free and unrestricted outward motion of the issuing mass of burnt g e pushing before it all the gases in its path, until it reaches the zone from which the return of the burnt gases would occur, and at such position imparting a gyratory motion to the said gases as a whole, which all rotate substantially in said position so that any subsequent rectilinear motion of the gases is hindered until the exhaust orifice is closed, maintaining the admission orifice closed until the said issuance of the mass of burnt gases is in full progress and admitting fresh charge into the cylinder when-the said issuance of the burnt gases is in full progress and causes a suction effect to be exerted in the cylinder. while the exhaust port is still open.

3. Method as claimed in claim 1, wherein said predetermined position is so located that the volume of the depression or void and the duration of the suction caused by the issuing mass of burnt gases is such that the said depression or void burnt gases and of a .prolonged outward movement of the burnt gases on the contents of the cylinder is avoided.

4. A two-stroke cycle internal combustion e'n-- gine wherein the burnt gases are discharged from the cylinder into an exhaust conduit substantially as a mass whereby the said mass -moves outward and thereafter returns towards the cylinder, the said conduit providing a free passage for the burnt gases to the limit, of outward travel of said mass, and wherein an inlet is opened for the introduction of fresh charge while the exhaust port is still open and when the said issuance of the burnt gases is in full progress and causes a suction effect to be exerted in the cylinder, hav- 'ing a chamber other than the engine cylinder in open communication with the exhaust conduit at a point situated. nearer'the cylinder than the limit of outward travel of the burnt gases upon their mass exit from the cylinder, means forming a part of the said conduit whereby the said mass is directed past the said communication during its outward motion and returning gases enter said chamber and a plurality of ad- -jacent openings. within said chamber provided for the outward motion of the issuing mass of burnt gases, and wherein an inlet is opened for the introduction of fresh charge while the exhaust port is still open and when the said issuance of the burnt gases is in full progress and causes a suction effect to be exerted in the cylinder. having a chamber inserted in the exhaust.

conduit at a point situated nearer the cylinder than the limit of outward travel of the burntgases upon their mass exit from the cylinder, a plurality of adjacent openings within said chamber provided with deflecting surfaces to impart yratory motion to the outwardly moving g and a baflie in said chamber to force said gases to flow through said openings.

6. A two-stroke cycle internal combustion engine wherein the burnt gases are discharged from the cylinder into an exhaust conduit substantially as a mass whereby the said mass moves outwards and thereafter returns towards the cylinder, the said conduit providing a free passa for the outward motion of the issuing mass of burnt gases, and wherein an inlet is opened fo the introduction of fresh charge while the exhaust port is still open and when the said issuance of the burnt gases is in full progress and causes a suction effect to be exerted in the cylinder, having a chamber inserted in the exhaust conduit at the limit of outward travel of the 'bumt gases upon their mass exit from the cylinforce said gases to flow through said openings.

hflCHEL KADENACY.

CERTIFICATE OF CORRECTION.

Patent No. 2,198,750. April 50, .19uo.

MICHEL KADENAGY.

It is hereby certified that the above numbered patent was erroneously issued to "Armstrong whitworth Securities Company, Limited as assignee of the entire interest therein whereas ssid patent should have been issued to the inventor, said "KADENACY" as sssignor of one-half interest to Armstrong Whitworth Securities Company, Limited, of London, England, as shown by the record of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this; 27th day of August, A. 1:. 191m.

Henry Van Ar'sdale, (Seal) Acting Commissioner of Patents.

- CERTIFICATE OF comcrxon. Patent No. 2,198,750. April 50, .19uo.

MICHEL KADENAGY.

It is hereby certified that the above numbered patent was erroneously issued to "Armstrong whitworth Securities Company, Limited" as assignee of the entire interest therein whereas said patent should have been issued to the inventor, said "KADENACY" as assignor of one-half interest to Armstrong Whitworth Securities Company, Limited, of London, England, as shown by the record of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this! 271:1; day of August, A. D. 19%.

Henry Van Ar'sdal'e, .1) Acting Commissioner of Patents. 

